I can go back to modify my Character after I put the Armature
Per my comment on your question, you appear to be in Pose Mode (which you referred to as 'armature mode'). If you hit Tab, you should be able to choose to switch instead into another mode. You'll want Edit Mode or Object Mode to get back into the basic modeling pipeline, or perhaps Sculpt Mode.

You can also control these options from the mouse-clickable menu in the bottom-left section of your 3D View window, which currently says Pose Mode in the image you posted. You can find this menu at the location indicated below: